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High School/JEE/NEET/IPhO Physics | 17-19 Yrs

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  1.  
    2. In 1:25 if joe is moving towards right....then the friction should act towards left...and same with the boat
    7 months ago by

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  2.  
    3. sir in this problem can we conserve the momentum
    1 years ago by Rajat Yadav

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  3.  
    4. sir what will be the direction of the velocity of car because values of variables are not given
    1 years ago by Rajat Yadav

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  4.  
    5. pls recheck the cel of child calculation, (M m) v - Mu/ m M minus sign is missing
    1 years ago by

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  5.  
    6. sir here u is root 2gh not eroot 2gh
    2 years ago by

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  6.  
    7. Sir in question variable 'h' is not given, so how can the final answer come in terms of h which is not there in question?
    2 years ago by

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  7.  
    8. Sir in question variable 'h' is not given, so how can the final answer come in terms of h which is not there in question?
    2 years ago by

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  8.  
    9. sir any other method for this problem ?
    2 years ago by kumar gaurav

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  9.  
    10. 3:07 why angles equal?
    3 years ago by

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  10.  
    11. lectures are not coming
    3 years ago by srinivasulu T

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  11.  
    12. why didn't we balanced the vertical component of the shell. As according to me sir, Ans. is 150i 100v3j
    3 years ago by

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  12.  
    13. What is the value of u?
    3 years ago by RUDRAKSH SINGHAL

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  13.  
    14. answer of the above problem is wrong as g will get cancelled from denominator and numerator.
    3 years ago by Rupali Bavaskar

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  14.  
    15. Sir, in the last illustration of this video it was given that the monkey is moving with speed 'u' RELATIVE TO STRING but you took 'u' as the speed of monkey relative to ground. Why??
    5 years ago by Vibhor Agrawal

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  15.  
    16. Hi Sir, first of all I’d like to thank you for uploading this video. Sir, I tried solving this question by using the ground frame of reference, and I supposed the spring force on each blocks to be kx(equal on each blocks), however, I was unable to reach to the final answer, but the, when I assumed two unequal force due to the spring on each block (kx1
    5 years ago by Kruthik Pimpre

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  16.  
    17. Sir why cant we conserve energy for m body only, i mean 1/2mu2 - mgh = 1/2mv2 ?
    5 years ago by ARCHAK SATAPTI

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  17.  
    18. normal force will also be acting on block which is not balanced by any other forDoes it will affect motion of block
    5 years ago by tukun saini

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  18.  
    19. sir how were you able to judge that it is head on collision??
    5 years ago by Divit Goyal

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  19.  
    20. sir how can we do it by relative velocity method??
    5 years ago by Divit Goyal

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  20.  
    21. sir why does boat displace??
    5 years ago by Divit Goyal

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  21.  
    22. if the friction is absent the time of sliding is same or or not
    5 years ago by vishal akula

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  22.  
    23. Aur i didn't understand why was the boy pulled by the string and even if he was won't the string slack
    6 years ago by Kunal Verma

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  23.  
    24. Respected Sir, here as u told there will be normal force equal and opposite in direction on both the bodies.So if i can say the IMPULSE given on the both the bodies are equal so can i EQUATE their impulse ? if no then why ?pls reply sir.....
    6 years ago by latanandb1

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  24.  
    25. If a vehicle is moving in horizontal direction with velocity v having mass M1, now if mass m2 is removed from it in downward direction, then what will be effect on vellocity
    6 years ago by

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  25.  
    26. sir if a block is moving with some velocity let us assume it as "U" on a smooth horizontal table and it is having friction on its top but not at the bottom which is in contact with the floor.Now suppose another block of mass "M" is drooped on to it while it is in motion now my doubt is will the bock slow down its initial speed "U"....i.e.,U initial will be greater than U final or not..Hope you understand my doubt..
    6 years ago by Neelesh
    Ans 1 ->
    obviously, due to addition of mass the velocity will decrease.i think ur doubt is about the friction in the surface.if that is the doubt then the exp goes like this, the block which u r keeping is staying on the second block only because of friction...(in the molecular level due to the friction present they are interlocked)
    6 years ago by latanandb1

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  26.  
    27. How does Cosine of theta becomes (2gl-u^2)/2gl
    6 years ago by Tushar kumar

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  27.  
    28. explanation of que set question 8 , 9
    6 years ago by

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  28.  
    29. Sir Since it is saying with respect to car which was moving with velocity v1 shoudnt it be u v1.
    6 years ago by

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  29.  
    30. An isolated particle of mass m is moving in horizontal plane [x-y], along x-axis at a certain height above ground. It suddenly explodes into fragments of masses m/4 and 3m/4. An instant later the smaller particle is at y=15 cm. The larger fragment at this instant is at-
    6 years ago by Ashok Kumar

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  30.  
    31. Thank you so much sir
    6 years ago by Shree Kant Sharma

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  31.  
    32. Sir , what's actually angular momentum ?? ...it's easy to understand ..torque ...as force ...and linear momentum as amount of motion possessed by a body...but how to think of angular momentum ...and how to know about which of it gets conserved...using law of conservation of momentum ?
    6 years ago by P.Ramyashri

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  32.  
    33. Sir it is m1v1costhetatwo and not m1v1costheta1
    6 years ago by Tejan Gupta

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  33.  
    34. wont the tension force be acting when the bullet hits the bob?? the how will yhe force external be zero??
    7 years ago by Kaanapuli RamKumar

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  34.  
    35. In the question it is specifically mentioned that mass M is scattered at 90 degree angle and so mass m should move at an angle of 60 degrees to the horizontal. Doesn't it? Answer then is 3/5?
    7 years ago by Udit Gupta

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  35.  
    36. A perfectly elastic ball is thrown from the foot of a plane whose inclination to the horizontal is ß. After striking the plane at a distance R from the point of projection it rebounds and retraces it path. Find the initial speed of throw.
    7 years ago by Akshit Monga

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  36.  
    37. Sir can we solve the above question using Work-energy Theorm?
    7 years ago by dhanush tummala
    Ans 1 ->
    Sry Got the answer
    7 years ago by dhanush tummala

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  37.  
    38. sir there are some concepts like reduced mass and centre of mass frame of reference which are not in the lectures and I c many question in test series which I often fail to cract it.. can u please upload those oncepts sir
    7 years ago by BHARADWAJ SUBRAMANIAM

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  38.  
    39. please explain what is this concept reduced mass?
    7 years ago by Omkar Choudhary
    Ans 1 ->
    It is already explained in booster classes...
    7 years ago by Physics Galaxy

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  39.  
    40. sir, in your solved examples in head on elastic collision, one question which u gave was -a neutron moving with a speed v undergoes HO ELASTIC COLLISION with a nucleus of mass A.Then why did we take mass of nucleus as mA???
    7 years ago by PUSHPASRI ROY

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  40.  
    41. hi sir how we can analyse the formulae and features of such rotating bodies
    7 years ago by hemanthsai

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  41.  
    42. Sir why initial momentum is mv and not mv + m(u-v)
    7 years ago by Anurag Dalmia
    Ans 1 ->
    because initially total mass was m and moving at speed v...
    7 years ago by Physics Galaxy

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  42.  
    43. Sir, if two masses m1 and m2 move with velocity u1 and u2 then during inelastic collision there velocity changes to u.How this happens as there is no restoring force??
    7 years ago by Anurag Dalmia

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  43.  
    44. respected sir in the solution of this illustration is the work done in com frame and the ground frame? that is x1 and x2 would get changed in ground frame?
    7 years ago by siddharth jain
    Ans 1 ->
    work done will be different in both frames but maximum extension of spring will be same... and x1 and x2 are defined in frame of com here and in ground frame both bodies would be moving in same direction of force...
    7 years ago by Physics Galaxy

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  44.  
    45. can we directly write that; total impulse imparted=final momentum of two bloks.. 250 = 3x30 + 2v hence v=80 is using com concept necessary here??
    8 years ago by nikita sadhnani

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  45.  
    46. sir can we apply lose in kinetic energy ??
    8 years ago by Nitesh Guleria

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  46.  
    47. A particle of mass m is moving horizontally with a constant velocity v towards a rigid wall that is moving in opposite direction with a constant speed u. Assuming elastic impact between the particle and wall, the work done by the wall in reflecting the particle is equal to A. (1/2)m(u + v) ² B. (1/2)m(u + v) C. (1/2)muv D. 2mu (u + v).
    8 years ago by Padmapriya Nagarajan

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  47.  
    48. sir can you explain this problem using any other method or give elaborate explanation ???????
    8 years ago by Obnoxious
    Ans 1 ->
    shut up and see this
    8 years ago by Tâŗųñ Şaì

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  48.  
    49. at 7:26 why in case of final momentum Mv-u is not written while mu-v is taken?
    8 years ago by Obnoxious
    Ans 1 ->
    Since the balloon is coming down the string will slack. The monkey is moving upwards it means he will pull and slacked string downwards hence his speed will decrease (by a factor 'v').
    8 years ago by Mayank Agrawal

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  49.  
    50. How is pseudo force acting in this system??as body is accelerating towards right so accn should also be towards right..
    8 years ago by Rajesh gupta

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  50.  
    51. in the question how momentum can be conserved if external gravitaional force is acting along line of motion???
    8 years ago by Rohan Aggarwal
    Ans 1 ->
    Because it is balanced by normal reaction....Notice the word NET Force. also momentum is a vector quantity and is being conserved along x axis not the y axis.
    8 years ago by Udayaditya Singh

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  51.  
    52. SIR IN SOME RARE CASES CAN THE CENTRE OF MASS BE OUTSIDE THE BODY BY ANY CHANCE
    8 years ago by SAI SMARAN S B
    Ans 1 ->
    YES Eg in ring and many other objecs
    8 years ago by Vishal Ray

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  52.  
    53. in this question is spring part of a system and spring force is internal force??
    8 years ago by Rohan Aggarwal

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  53.  
    54. sir in example 18 we assumed that the ball m moves horizontally and on the axis where the M ball is placed...so what about line of impact? how can u conserve the momentum in x and y direction so firmly without knowing the direction of line of impact which can be either of x and y axis? plz reply as soon as possible..
    8 years ago by Khushboo Jain

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  54.  
    55. sir since the displacements of the block hance the spring is different .i.e. x1 and x2... the spring force on the blocks will also be different..isn't it? secondly why we r ignoring the spring forces on the blocks? plz reply as soon as possible..
    8 years ago by Khushboo Jain

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  55.  
    56. sir in example 4 how can u say that the second fragment will definitely go in the horizontal direction only.... according to me if we equate the momentum of the particle at the projected point and the explosion point we will definitely get a component of velocity of second particle in y direction..i think the answer solved here is incomplete ... isn't it? plz reply as soon as possible
    8 years ago by Khushboo Jain
    Ans 1 ->
    sir calculated momentum at highest point where y component vanishes
    6 years ago by VARUN a

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  56.  
    57. is there any other way to solve the above question ?
    8 years ago by bharat tiwari

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  57.  
    58. Sir u r taking more time to answer our questions.. I'm studying in Narayana iit so I had only 1 week time for studying each chapter.. So please answer my question some fast
    8 years ago by sandeep

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  58.  
    59. Two identical blocks A and B of mass M each are kept on each other on a smooth horizontal plane. There exists friction between A and B. If a bullet of mass m hits the lower block with a horizontal velocity v and gets embedded into it. Find the work done by friction between A and B.
    8 years ago by Atharva Sarage

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  59.  
    60. I connect two balls of unequal masses by a string(ideal),and hit one of them at some angle to the line joining them.Then the momentum J is given to the system or just the one ball,in this case how can i calculate the velocities of the mass and the angle is given?
    8 years ago by Rahul Ojha

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  60.  
    61. Sir as you said the inelastic materials donot have any restoring force. So assume 1st body to move with velocity u1 and 2nd body with vel. u2 (u1 is greater than u2) thus when they have impact since there is no restoring force how the vel. u1 decreases and vel. u2 increases and ultimately become equal (i.e. u) at some instant ??
    8 years ago by ayush kumar tripathi
    Ans 1 ->
    what u r talking about is of elastic collision or partially elastic collision. in inelastic collision bodies do not regain shape and remain attached together so no change in velocity will take place after they attain a constant velocity after collision. F external in zero in this case.
    8 years ago by Sangita Kumari

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  61.  
    62. Here centre of mass wouldn't be 8/5m??as both have different masses.
    9 years ago by Niraj rajai
    Ans 1 ->
    It is 8/5
    8 years ago by Anudeep Kicks
    Ans 2 ->
    sir can you explain this problem using any other method or give elaborate explanation ???????
    8 years ago by Obnoxious

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  62.  
    63. Sir, since we are taking x1 and x2 as displacements,so, should not there be x2 as positive and x1 as negative? since x1 is moving in -X direction and x2 is moving in +X direction?
    9 years ago by Vineet Chatterjee
    Ans 1 ->
    Here to calculate work +ve or -ve we need to consider direction of x if it is along F or opposite to F... If direction of displacement is in the direction of Force we will take work positive otherwise negative... I hope you can get it now...
    9 years ago by Physics Galaxy

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  63.  
    64. wouldn't the answer to the second part... i.e. max..separation will be '' L+F/k '' because we are taking x1 and x2 as displacements ... right...??
    10 years ago by Ocean Balodiya
    Ans 1 ->
    In the above solution I have calculated the maximum displacements of the blocks so max displacement will be lo + F/k.
    9 years ago by Physics Galaxy

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